It is desirable to be able to selectively heat the outer surface of food products in order to for example heat-set coatings, heat-sear food products to provide an improved crisp outer surface or selectively thaw the outer-most surface of a frozen product.
Furthermore, it has been recognised for a long time that it is beneficial to reduce the fat content of food products. Conventionally certain food products, for example coated food products, potato chips, are pre-fryed in order to seal the coating and/or provide a crisp outer surface. Such a pre-frying process results in a higher quantity of fat/oil being absorbed by the food product than is required for producing the desired end result.
U.S. Pat. No. 4,800,090 (Musser's Potato Chips Inc) discloses a process and apparatus for preparing potato chips without the use of oil comprising subjecting the potato slices to standard infra-red having a maximum of 50 kW/m.sup.2, followed by exposing the sliced potato pieces to a sufficient amount of standard infra-red to achieve browning. Such a process will not restrict the heat to the surface only and requires much greater exposure times to the heat source.
GB 2 206 026 (Havethill Meat Products Ltd) discloses the use of high intensity short wave infra-red to provide sausages with sear marks conventionally provided by cooking sausages on a charcoal grill. The heat source for such an application is necessarily highly focused and the utility of high intensity short wave infra-red for total surface heating is not disclosed.